java把多个url压缩成zip, 前端接收返回的字符串并下载

说明: 后端把多个url转成字节数组，并合成zip供前端下载。

1. 把url的转成字节数据

public static byte[] getFileUrlByte(String fileUrl) throws BusException {
        try {
            URL url = new URL(fileUrl);
            HttpURLConnection urlCon = (HttpURLConnection) url.openConnection();
            urlCon.setConnectTimeout(6000);
            urlCon.setReadTimeout(6000);
            int code = urlCon.getResponseCode();
            if (code != HttpURLConnection.HTTP_OK) {
                throw new BusException("文件读取失败");
            }
            InputStream is = url.openStream();
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();

            byte[] bytes = new byte[BYTE_LENGTH];
            int length = 0;
            while ((length = is.read(bytes)) != -1) {
                outputStream.write(bytes, 0, length);
            }
            outputStream.close();
            is.close();
            return outputStream.toByteArray();
        } catch (IOException e) {
            log.error("文件下载异常: {}", ExceptionUtil.stacktraceToString(e));
            throw new BusException(String.format("文件下载失败, %s", e.getMessage()));
        }
    }

2.把多个文件流合成zip输出流

public static byte[] regularZipByte(List<FileInfo> fromFiles) throws BusException {
        byte[] arr = new byte[0];
        try {
            Random random = new Random();
            @Cleanup
            ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
            @Cleanup
            ZipOutputStream zipOut = new ZipOutputStream(outputStream);
            // 如果有重复的名称, 则重命名
            Set<String> fileNameSet = Sets.newHashSet();
            for (FileInfo fileUrl : fromFiles) {
                String fileUrlTemp = fileUrl.getFileUrl();
                int index = fileUrlTemp.lastIndexOf(ProjectConstant.SLASH);
                String urlPrefix = fileUrl.getFileUrl().substring(0, index + 1);
                String originalFileName = fileUrl.getFileUrl().substring(index + 1);
                String entryName = originalFileName;
                if (fileNameSet.contains(entryName)) {
                    if (entryName.contains(ProjectConstant.POINT)) {
                        String[] split = entryName.split(ProjectConstant.POINT_ESCAPE);
                        entryName = split[0] + random.nextInt(9999) + ProjectConstant.POINT + split[1];
                    } else {
                        entryName += random.nextInt(9999);
                    }
                }
                byte[] fileUrlByte = getFileUrlByte(urlPrefix + URLEncoder.encode(originalFileName, "UTF-8"));
                fileNameSet.add(entryName);
                zipOut.putNextEntry(new ZipEntry(entryName));
                zipOut.write(fileUrlByte);
            }
            zipOut.finish();
            outputStream.flush();
            arr = outputStream.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
            throw new BusException("下载异常");
        }
        return arr;
    }

3. 前端接受接口返回的字节数组, 并解析下载

testBtn4 () {
      axios({
        method: 'get',
        url: 'http://localhost:端口/地址'
      }).then((data) => {
        var raw = window.atob(data.data)
        var uInt8Array = new Uint8Array(raw.length)
        for (var i = 0; i < raw.length; i++) {
          uInt8Array[i] = raw.charCodeAt(i)
        }
        const blob = new Blob([uInt8Array], {
          type: 'application/octet-stream'
        })
        const link = document.createElement('a')
        link.style.display = 'none'
        link.href = URL.createObjectURL(blob)
        link.download = '导出文件' + Date.parse(new Date()) + '.zip'
        document.body.appendChild(link)
        link.click()
        document.body.removeChild(link)
      })
    },

备注：
后端返回的格式